Steel furniture is appreciated because of its easy assembly, modern types etc., particularly furniture which combines steel with fabric, such as sofas, folding sofa beds, steel camp beds, etc. The steel wire netting on conventional steel furniture, e.g., the net mattress of a camp bed, is made of a steel wire netting with a frame. The steel wires are connected to the frame using dot welding. However, this leads to disadvantages that the steel wire netting may easily distend and deform, and it is difficult to maintain the tension in the netting.
In order to enable a camp bed to maintain tension in the netting, patent No CN 97238776 describes a composite steel wire camp bed in which the steel wires are tensed by a frame. The frame includes two cross rails and four longitudinal rails. Longitudinal rails are secured to each other by connection shafts and cross rails are secured to longitudinal rails by right connection braces at the four corners where longitudinal rails and cross rails intersect. Camp beds of this type can maintain tension in the wire netting, and flexible bearings can be installed underneath, which allows users to lie in comfort and prevents the surface of the bed from distending downwards. However, this structure includes too many components and the connection structure is complex. In addition, the production process is complex, which increases the cost. Therefore, it is difficult to use the above structure widely in sofas, sofa beds and the like.